Roblox Script Generated by ScripterAI

"Can you correct the script please its as following: BillboardGui>Mat>TeleporterScript, PartA, PartB, wall1, wall2, wall3, wall4, wall5"

I believe the script you provided is almost correct, but it seems like you're having trouble with the structure of your workspace. Here's how your workspace should be structured:

```
Workspace
├── Mat
│   └── TeleporterScript
├── PartA
├── PartB
├── wall1
├── wall2
├── wall3
├── wall4
└── wall5
```

And here's the corrected script:

```lua
local mat = game.Workspace.Mat
local teleportPartA = game.Workspace.PartA
local teleportPartB = game.Workspace.PartB
local walls = {game.Workspace.wall1, game.Workspace.wall2, game.Workspace.wall3, game.Workspace.wall4, game.Workspace.wall5}
local billboardGui = Instance.new("BillboardGui")
local textLabel = Instance.new("TextLabel")

billboardGui.Adornee = mat
billboardGui.Size = UDim2.new(0, 200, 0, 50)
textLabel.Parent = billboardGui
textLabel.Size = UDim2.new(1, 0, 1, 0)
textLabel.TextScaled = true

local playersOnMat = {}

local function teleportPlayers()
    local players = game.Players:GetPlayers()
    for i, player in ipairs(players) do
        if playersOnMat[player] then
            if i == 1 then
                player.Character.HumanoidRootPart.CFrame = teleportPartA.CFrame
            elseif i == 2 then
                player.Character.HumanoidRootPart.CFrame = teleportPartB.CFrame
            end
            player.Character.HumanoidRootPart.CFrame = player.Character.HumanoidRootPart.CFrame * CFrame.Angles(0, math.pi, 0)
        end
    end
end

local function updateGui()
    if #playersOnMat == 2 then
        billboardGui.Parent = mat
        for i = 5, 1, -1 do
            textLabel.Text = tostring(i)
            task.wait(1)
        end
        teleportPlayers()
        for _, wall in ipairs(walls) do
            wall.Transparency = 1
            wall.CanCollide = false
        end
    else
        billboardGui.Parent = nil
    end
end

local function onPlayerEntered(otherPart)
    local player = game.Players:GetPlayerFromCharacter(otherPart.Parent)
    if player then
        playersOnMat[player] = true
        updateGui()
    end
end

local function onPlayerLeft(otherPart)
    local player = game.Players:GetPlayerFromCharacter(otherPart.Parent)
    if player then
        playersOnMat[player] = nil
        updateGui()
    end
end

mat.Touched:Connect(onPlayerEntered)
mat.TouchEnded:Connect(onPlayerLeft)
```

In this script, the `Mat` part is expected to have the `TeleporterScript` as a child. The `PartA`, `PartB`, and `wall1`-`wall5` parts are expected to be siblings of `Mat` in the Workspace.